Redhat Linux Interview Questions and Answers part 11

Q: – /proc/ directory contains a number of directories with numerical names. What is that?

These directories are called process directories, as they are named after a program's process ID and contain information specific to that process.

Q: – What is the difference between hardware RAID and Software RAID?

The hardware-based RAID is independent from the host. A Hardware RAID device connects to the SCSI controller and presents the RAID arrays as a single SCSI drive. An external RAID system moves all RAID handling "intelligence" into a controller located in the external disk subsystem. The whole subsystem is connected to the host via a normal SCSI controller and appears to the host as a single disk.

Software RAID is implemented under OS Kernel level. The Linux kernel contains an MD driver that allows the RAID solution to be completely hardware independent. The performance of a software-based array depends on the server CPU performance and load.

Q: – What are the commonly used RAID types?

RAID 0
RAID 1
RAID 5

Q: – Explain RAID 0?

RAID level 0 works on “striping” technique. In RAID 0 the array is broken down into strips and data is written into strips. RAID 0 allows high I/O performance but provides no redundancy. RAID 0 Array Size is equal to sum of disks in array. If one drive fails then all data in the array is lost.

Q: – What is RAID?

RAID, stands for Redundant Array of Inexpensive Disks. RAID is a method by which same data or information is spread across several disks, using techniques such as disk striping (RAID Level 0), disk mirroring (RAID Level 1), and disk striping with parity (RAID Level 5) to achieve redundancy, lower latency, increased bandwidth, and maximized ability to recover from hard disk crashes.

Q: – Why should we use RAID?

System Administrators and others who manage large amounts of data would benefit from using RAID technology.

Following are the reasons to use RAID
– Enhances speed
– Increases storage capacity using a single virtual disk
– Minimizes disk failure